Shower Head Fluid Simulation: Domain too big issue
If splashing is not important why not use particles in fluid mode with a metaball render object.



Use many thousands of particles with a short life (until they fall out of frame).




Add a metaball with very high resolution and set it to the render type.



Also I add Denoiser (B2.79) to clean up the surface of the water for animation. And I have added Children Particles in Simple mode. Just a multiple of 3.



Sadly I cannot get the motion blur to work on particles.